Appear in shops and next to the elevator to the next floor
When at full HP, you can interact with heart or half heart pickups lying on the floor to "Save Them for Later" (which causes the pickup to disappear)
Interacting with the vending machine will drop one of the saved heart/half hearts
The hearts can be retrieved on future floors

Tanned Ammo Box

Gives the selected gun 50% of its total ammo
Gives all other guns 25% of their total ammo

Hey Gungeoneers! We wanted to give you all an update on AG&D and what we’ve been up to these past few months, as well as apologize for being late and our up-to-now radio silence.

First and foremost, what you can probably guess: we've been working hard to ensure our Advanced Gungeons & Draguns update is up to the quality that you have hopefully come to expect from us, but we have hit a couple of major delays.

The Switch version took far more time and resources than we initially expected. We have help with our ports, and we assumed initially that porting to Switch would not be substantially more complicated than porting to Xbox One, but the Switch version needed very low-level restructuring in a way that only someone with intimate knowledge of how the game was architected could accomplish in any reasonable amount of time. This is stuff we almost certainly would’ve had to do before our next update (after AG&D), so it isn’t strictly Switch-specific, but we had to adjust our timetable substantially. Once it was completed, there were of course the normal several weeks of further support and bug-fixing. In short, the Switch version became considerably more of a time-sink than we had anticipated, and ground the development of AG&D to a crawl. We've been working full-time on the update for weeks now, and we are happy to report things are going smoothly.

(For the curious: due to certain requirements as part of the Switch specification we had to completely rewrite how Gungeon stores and loads objects in and out of memory, which, as I'm sure you can imagine, is a pretty fundamental part of the game. The good news is, this reduced the filesize of Gungeon substantially, from about a gigabyte to around three hundred megabytes on Switch. This is an improvement that will come to other platforms, though the specific size changes might vary.)

The second delay came from some indecision as to what to include in AG&D and what to include in possible future updates. In our usual way, we kept adding stuff to AG&D until it had grown substantially beyond our original announced plans. This, coupled with the Switch interruption, meant that we spent a decent amount of time working on content that ultimately will probably be included in an update after AG&D. This is good news in a way, in that it means we're ahead of schedule on a future update... but obviously was bad news in the short run for AG&D. That said, we're absolutely not cutting anything we've announced for AG&D--all this additional content is secret stuff we've not talked about yet! Anything you've heard us say will be in AG&D absolutely will still be.

Basically, we put too many bullets in the chamber at once. We'll do another update once we're absolutely certain of a release date for AG&D, in the same way that we only announced a Switch release date right before it came out. In fact, this will almost certainly just become Dodge Roll policy; we'll still announce cool stuff, but we're just really bad at making date predictions. This makes the official release date of AG&D “soon," where "soon" means "more than a week and less than four months." Our apologies for having psyched you up so far in advance, and thank you very much for your continued patience and support for us. We're lucky to have a really supportive community, and honestly we can't wait to have you play through what we've got in store. A lot of it will be welcome changes, and some of it, we're sure, will be a sadistic surprise.

EDIT: I'd just like to add how unbelievably nice it is to see all of the thanks and the nice comments in the responses. I was really tempted to reply to all of you! Please know that it is super appreciated.

Enter the Gungeon’s Advanced Gungeons & Draguns Update is a free update that will be released mid 2018. It features approximately 30 items and guns, new rooms, a secret floor with the Resourceful Rat as a boss, approximately 350 new synergies, new NPCs, and various balance changes. Certain elements from this update have been found in regular gameplay on the Nintendo Switch version of the game.

Alright, so here's a (very long) explanation of how to reach both the Rat boss and the Advanced Dragun. Read at your own risk:

SPOILERS AHEAD

In order to get to the Rat boss you have to first buy or steal the Gnawed Key in the shop of the second floor. Paying money for it will reduce the price permanently, this way you can lower the prize to 115 casings over multiple runs which is barely enough so you can get it on almost every run.
Then you need to find a trap door on the 3rd floor. It will spawn in a random room with enemies in it and there will be small rats running around in this room too. To find the trap door, walk all over the room and pay attention to the dust your steps create. If the cloud of dust is bigger than usual then that's where the door is. Walk back and forth on that spot and it will become visible.
Now you need one normal key or another way to open the lock (like Drill, Lockpicks or A-Key 47). Once you go inside you'll see a long corridor. Go all the way to the end and use a blank. This will open a secret wall. At the end of the opened passage, use another blank. Behind this second opened wall you will see a sewer-like floor gate which requires the Gnawed Key. Jumping in will bring you to the Rat's maze.

Now, how to navigate the maze? You may have noticed that the Rat sometimes steals the contents of chests and replaces them with notes. He will do this a total of 6 times and leave a different note every time. The notes will be recorded in the items section of your Ammonomicon. Every note has an image of a piece of cheese on it that points in a certain direction. These directions are the ones you have to go in the maze. The order of the notes is (in the Ammonomicon) from top to bottom and left to right as you'd expect.
If you follow these directions (which are different for every safe file) then you will reach the Rat's room.

Beating the Rat is a prerequisite for being able to fight the Advanced Dragun.
Make sure to do well in the last phase of the Rat fight because you need two of the special keys he can drop for this. Use a blank in the room with the four big chests. This will open a secret passage where you have to use the two keys to open a cage. In the cage is a sleeping baby Dragun. To make it wake up, feed it 3 items or guns by dropping them next to it. Anything works except for Junk.
From this point on it will follow you. Take it to the Dragun and he will transform once his heart is revealed.
Good luck.﻿